Process for producing sulfonic acids and sulfonates



Patented Dec. 18, 1951 PROCESS FOR PRODUCING SULFONIC ACID ANDSULFONATES Henry W. Anderson, Martinez, Otto A. Samson, Concord, andAugustus W. Clark, Albany, Calif., assignors to Shell DevelopmentCompany, San Francisco, Calif., a corporation of Delaware No Drawing.Application August 21, 1948, Serial No. 45,588

Claims.

This invention relates to the preparation of organic sulfonic acids andsulfonates, and particularly to sulfonic acids and their derivativesalts which may be prepared by the treatment of :petroleum oils with asulfonating agent. The invention is concerned more particularly with thepreparation of oilsoluble petroleum sulfonic acids and sulfonates, oftendesignated mahogany sulfonic acids and sulfonates.

It is well known to acid-treat various hydrocarbon oils with strongsulfuric acid for the purpose of improving certain qualities of the oil,by removing substances therefrom which impart undesirable properties tothe oil. Various reaction products are formed in this treatment,including sulfonic acids, some of which are oil-soluble and someoil-insoluble or water-.soluble, the amounts depending upon factors suchas the nature of the oil, the severity of acid-treatment, and the like.It is also well known to recover these sulfonic acids by variousmethods, as incidental to the purification of the oil. Various methodsare also practiced where the principal purpose is to produce eitheroil-soluble, mahogany, acids or water-soluble, green acids, or both,since the former have been found to be of increasing value inhydrocarbon oil compositions, such as lubricating compositions, and thelatter are particularly valuable in the preparation of insecticidalspray compositions.

In the preparation of oil-soluble mahogany acids and soaps, it has beenthe general practice to treat a suitable oil stock, such as alubricating oil distillate, with a suitable sulfonating agent such asconcentrated or fuming sulfuric acid at normal atmospheric or elevatedtemperatures, and with agitation, until satisfactory reaction takesplace, to permit the reaction mixture to stand in a quiescent state sothat the formed sludge, generally containing resinous material, excessacid and oil-insoluble sulfonic acids, may separate as a lower layerfrom the oil and oilsoluble sulfonic acids dissolved therein. Afterseparation of the two layers, the sulfonic acids in the oil layer arerecovered therefrom, either as the free acid or salt thereof, byextraction with an aqueous alcoholic solution of a lower molecularweight alcohol, such as methanol, ethanol, and propanol. The solvent isthen distilled from the aqueous alcoholic solution of the neutralizedacid to yield the sulfonate, generally admixed with a substantialproportion of 'oil and an appreciable amount of inorganic salts. Variousmethods have been proposed for subsequent purification of thesulfonates.

in the oil phase in the practice of the foregoing method, as applied tothe rafiinate from a solvent extraction of a lubricating oil distillatefraction, have been found to be of the order of five to nine per cent,based on the weight of the oil charge.

It is a principal object of this invention to provide an improvedprocess for the preparation of oil-soluble petroleum sulfonic acids andtheir salts. A further object is to increase the yield of sulfonic acidsseparated in the oil phase of a sulfonation treatment of hydrocarbonoils. Another object is to increase the recovery of mineral oil in thesulfonation process. A more specific object is to provide a methodwhereby a hydrocarbon oil concentrate of oil-soluble petroleumsulfonates in higher concentration is obtainable directly from asulfonation treatment of a hydrocarbon oil, or fractions thereof,particularly a solvent extraction raflinate of a petroleum oildistillate fraction having lubricating viscosity.

Now, in accordance with the present invention,

.it has been found that an improved yield of oilsoluble petroleumsulfonates in the oil phase and an increase in.yield of oil phasegreaterthan can beaccounted for solely on the basis of increased recovery ofsulfonic acids, indicating that some mineral oil which would otherwisebe retained in the sludge phase is transferred to the. oil phase. isobtained by the method which comprises in combination the steps of,intimately contacting a hydrocarbon oil, preferably of naphtheniccharacter and of lubricating viscosity, with a suitable sulfonatingagent, such as fuming sulfuric acid, chlorsulfonic acid, sulfur trioxidein the presence of sulfur dioxide or other suitable catalyst, andpreferably concentrated, including fuming, sulfuric acid, under suitableconditions of time and temperature to effect substantial sulfonation ofthe hydrocarbon oil and thereafter, and preferablybefore sludgeseparation, admixing a predetermined proportion of water with thereaction mixture to produce, upon being allowed to stand in a quiescentstate, a lower aqueous acid layer and an upper oil layer, and separatingthe two layers, the proportion of water being such as to produce anaqueous acid phase of from about 50% to about sulfuric acidconcentration. The proportion of water added will depend, as will bereadily understood, on the concentration of the sulfonating acid at thetime the water is added, which, in turn, will depend on the originalacid concentration, the ratio of acid used to oil charge, and theproportion of sulfonatable materials present in the oil under theconditions of sulfonation.

Representative yields of sulfonates recovered By practicing the presentinvention. as deavas 3 scribed broadly hereinbefore, anumber of seriousproblems encountered in prior methods are at least partially orsubstantially entirely obviated. Thus, where the addition of smallamounts of water to the sulfonation mixture has been proposed, with morethan a few per cent of water addition there results the formation of twosludge phases, one a dilute acid phase, the other a thick,

difiicultly pumpable, tar phase, the proportion of tar phase increasinwith an increase in the proportion of water added. It has now beenfound, however, that maximum tar separation is reached when water isadded in amount to separate a sludge acidity in the range of about 75%to about 80% sulfuric acid concentration, as may be produced when aboutby weight of water is added, based on the weight of equivalent 100%sulfuric acid present. The addition of still larger proportions of waterresults in the separation of smaller amounts of tar with the amountbeing of the order of only 0.1% to 0.3% by weight, based on the oilcharge, for sludge acidities below about 65% by weight sulfuric acid.The resulting sludge mixture is readily pump able. On the other hand, asthe acid sludge is diluted with water its corrosive action on metalequipment which is normally used in the settlers and the like increasesrapidly so that there is a limit to the amount of dilution which ispermissible. For an acidity corresponding to about 100% sulfuric acidthe corrosion is at a minimum, but below a concentration of about 60%sulfuric acid, the corrosivity is rapidly approaching a value whichcannot be tolerated. Considering the two factors, pumpabality (tarseparation) and corrosivity, it may be stated that in general theaddition of sufficient water to give a sludge acidity of from about 50%to about 70% sulfuric acid, and preferably from about 60% to about 65%sulfuric acid, to the sulfonation mixture immediately after thesulfonation and prior to appreciable sludge separation, results in areadily pumpable sludge and one which is substantially non-corrosive.

Another problem is the rate of separation of the sludge and oil phases.Although it has been proposed to add 100% or more of water, relative tothe acid, particularly in the preparation of water-soluble, green acidsfrom light, non-lubrieating, hydrocarbon oils, such as kerosene andstove oil, in order to increase the recovery of water-soluble acids. and-it might be expected that such dilution would enhance phase separationdue to dilution of the acid, it has been found that in the presentinvention, concerned with recovery of mahogany acids, after sulfonationtreatment, the sludge settling rate, or phase separation rate, is at amaximum when the sludge acidity is between about 70% and about 75%sulfuric acid, corresponding in general to the addition of from about toabout water, with the rate decreasing both as the sludge acidity isdecreased or as it is increased. From the standpoint of sludge settlingrate, it is preferred to adjust the sludge acidity at 70% to 75%sulfuric acid but settling rates are still satisfactory andsubstantially higher than the rate when no water is added at sludgeacidities as low as sulfuric acid.

Now, concomitant with the foregoing-described advantages gained by thedilution step with water, it has also been found that the amount ofsulfonic acid separated in the stratified oil layer is materiallyincreased, represen- 10% to about 18% by weight, based on the oilcharge, the maximum recovery being found at a sludge acidity of about tosulfuric acid and beginning to drop offrapidly at sludge aciditiesgreater than about Having set forth various advantages to be gained inthe practice of the invention, the manner in which the invention is tobe practiced will be described in greater detail.

Various petroleum hydrocarbon oils and fractions thereof, particularlythose which possess lubricating properties, and are of the so-calledmixed type, i. e. containing naphthenic type hydrocarbons, may beutilized for the preparation of oil-soluble sulfonates by the process ofthis invention. In general, it is preferred to use hydrocarbon oilfractions derived from naphthenic Gulf Coastal, Mid-Continent orCalifornia oils, and particularly the lubricating oil fractions obtainedfrom such crudes. Prior to sulfonation the oil may be solvent treated.

A naphthenic oil which is particularly useful for the production of theoil-soluble sulfonic acids may be a furfural or an Edeleanu rafllnate ofa naphthenic oil distillate having the followin properties:

Viscosity SSU at 100 F 40Qt0 900 Viscosity index 30to 60 Gravity, API 22to 27 Refractive index N 1.48 to 1.51 Flash (0. O. C.) F 380 to 450tative recoverable amounts being from about 75 Representative ofsuitable oil stocks which have been used were 33 V. I. and 55 V. I.rafiinates from solvent extraction of 60 SSU at 210 F. bulk distillatesderived from an /20 Poso/Coalinga, California crude mixture. Thesolvents may be sulfur dioxide, furfural, phenol or the like.

The method of obtaining the advantages of the invention is illustratedby the following example.

A 55 V. I. rafilnate, as described hereinbefore. was intimatelycontacted with 20% of its weight of 105.5% fuming sulfuric acid (25%S03), 103.5% to 105.5% acid generally being preferred,

, while maintaining the temperature below about 150 F., and generallyabove about 75 F., preferably above F., for a period of about 10minutes. Higher temperatures, such as up to about 200 F., may be usedfor shorter periods of time. Most of the sulfonation is completed withinabout ten minutes, a further small amount of sulfonation being effectedwhen the time is extended to about 30 minutes. Excessive contactingtimes may result in sludge separation during the sulfonation, which itis desired to avoid in the present invention. The contacting of the oiland sulfuric acid may be readily carried out in a single stage operationas in a batch process or any other operation as will be understood whichlends it self to the practice of the invention. After the oil-acidmixture had been intimately contacted for 10 minutes, an amount of watersquivalent to 25% by weight of the weight of fuming acid used, 1. e. 5%by weight of the oil charge, was added, in the absence of anyneutralizing basic substance, mixed thoroughly with the reactionmixture, and the phases allowed to stratify. The separated oil phaserepresented about 97% by weight of the oil charge and contained 11.5% byweight of sulfonic acid. The separated aqueous sludge layer had anacidity of about 70% by weight hydrogen sulfate (H2804) was readilypumpable, and was not excessively corrosive to.- ward the iron settlingvessel and carrying lines.

When another charge of the same oil was treated as in the foregoingexample, except that no water was added prior to settling andstratiflcation of the different reaction-mixture phases, the separatedoil phase amounted to only about 86% of the charge and the sulfonic acidcontent thereof was only about 6% by weight.

In another case similar to the foregoing examples, but adding about 45%watenthe separated oil layer was about 99% by weight of the oil chargeand it contained approximately 13.5% by weight of sulfonic acids.

In still another instance similar to the first above-described example,but using 30% by weight acid dosage and 33% subsequent water addition,the separated oil layer contained about oil-soluble sulfonic acids. Bythe use of a still higher acid dosage, such as 50%, and a correspondingwater addition to yield a sludge phase of approximately 70% acidity, anoil phase has been obtained which contained about 18% by weight ofoil-soluble sulfonic acids.

The separated oil solutions of sulfonic acids as prepared in theforegoing examples in accordance with the invention were converted to'oil solutions of the corresponding calcium petroleum sulfonates bymethods well known to the art, such as by reacting directly with calciumoxide or hydroxide, or with an aqueous mixture of calcium chloride andcalcium hydroxide, or by converting to an oil solution of the sodiumsulfonate by reaction with a sodium alkali compound and then conversionof the sodium salt to the calcium salt by metathetical reaction. Theconcentrates of calcium petroleum mahogany sulfonates thus produced werefound to be highly effective in the production of motor lubricating oilsand other oil compositions containing the sulfonate. 4

Thus, the practice of the invention makes it possible to obtain agreater recovery of oil-soluble sulfonates in the oil solution. Animportant advantage derivable therefrom is that the resulting sulfonatesolution contains a higher concentration of active ingredients andconsequently, smaller amounts of the oil carrier (in the concentrate)need be incorporated with the oil to which it is desired to add thesulfonates.

The reason why the practice of the invention results in a greaterconcentration of the oil-soluble sulfonates in the oil is not known withany degree of certainty. However, and without being limited as to anytheory concerning the matter, it may be that the water addition prior tosludge separation minimizes further reaction, including possiblepolymerization of already-formed oilsoluble sulfonates, and/ or furthersulfonation to oil-insoluble disulfonic or polysulfonic acids, and alsothat the water addition at that time results in a sulfuric acid phasewhich is not capable of retaining an appreciable proportion of theoilsoluble sulfonates in solution therein, which otherwise would becapable of carrying oil-soluble sulfonic acids into the sludge phase.The facts appear to indicate that the increased recovery of oil-solub lsulfonic acids in the oil phase is not attributable solely, if at all,to a transfer of water-soluble and normally oil-insoluble sulfonic acidsinto the oil phase.

We claim as our invention:

1. A process for the production of an oil solution of oil-solublepetroleum sulfonic acids dissolved in a highly refined lubricating oilfraction, which process comprises intimately contactinga minerallubricating oil raflinate fraction of naphthenic character, having aviscosity at 100 F.

of at least about 400 SSU, a viscosity index of from about 30 to 60, aflash point of atv least about 380 F., and having been obtained asrafiinate fraction from a selective solvent extraction of a naphthenicmineral lubricating oildistillate fraction, with 20% to 50% by weight,based on the oil charge, of 105.5% fuming sulfuric acid, at atemperature between about F. and 150 F. for a period of about 10minutes, thereafter immediately and before the separation of a sludgephase, intimately mixing the resulting reaction mixture with from about25% to about by weight of water, based on the acid used, selected toyield a separated acid sludge phase with an acidity of from about 50% toabout 70%, permitting the resulting admixture to stratify wherea by onlytwo layers are formed, an oil layer containing dissolved oil-solublepetroleum sulfonic acids and an acid sludge layer, and separating thelayers.

2. A process for the production of an oil solution of oil-solublepetroleum sulfonic acids, which process comprises intimately contactinga mineral lubricating oil rafllnate fraction of naphthenic character,having a viscosity at F. of at least about 400 SSU, a viscosityindex offrom about 30 to about 60, a flash point .of at least about 380 F., andhaving been obtained as a raflinate fraction from a selective solventextraction of a naphthenic mineral lubricating oil distillate fraction,with 20% to 50% by weight, based on the oil charge, of 103.5% to 105.5%fuming sulfuric acid, at a temperature between about 75 F. and F. for aperiod of about 10 minutes, thereafter immediately and before theseparation of a sludge phase, intimately mixing the resulting reactionmixture with from about 25% to about 80% by weight of water, based onthe acid used, selected to yield a separated acid sludge phase with anacidity of from about 50% to about 70%, Permitting the resultingadmixture to stratify whereby only two layers are formed, an oil layercontaining dissolved oilsoluble petroleum sulfonic acids and an acidsludge layer, and separating the layers.

3. A process for the production of an oil solution of oil-solublepetroleum sulfonic acids, which process comprises intimately contactinga mineral lubricating oil railinate fraction of naphthenic character,and having been obtained as a rafllnate fraction from a selectivesolvent extraction of a naphthenic lubricating oil distillate fraction,with 20% to 50% by weight, based on the oil charge, of 103.5% to 105.5%fuming sulfuric acid, at a temperature between about 75 F. and 150 F.for a period of about 10 minutes, thereafter immediately and before theseparation of a sludge phase, intimately mixing the resulting reactionmixture with from about 25% to about 80% by weight of water, based onthe acid used, selected to yield a separated acid sludge phase with anacidity of from about 50% to about 70%, permitting the resultingadmixture to stratify whereby only two layers are formed, an oil layercontaining dissolved oil-soluble petroleum sulfonic acids and an acidsludge layer, and separating the layers.

4. A process for the production of an oil solution of oil-solublepetroleum sulfonic acids, which process comprises intimately contactinga mineral lubricating oil rafilnate fraction of naphthenic character,having a viscosity at 100 F. of at least about 400 SSU, a viscosityindex of from about 30 to about 60, a flash point of at least about 380F., and having been obtained as a raflinate fraction from a selectivesolvent extraction of a naphthenic mineral lubricating oil distillatefraction, with to 50% by weight, based on the oil charge, of fumingsulfuric acid, at a temperature between about 75 F. and 150 F. for aperiod of not more than about 10 minutes, thereafter immediately andbefore the separation of a sludge phase, intimately mixing the resultingreaction mixture with from about to about 80% by weight of water, basedon the acid used, selected to yield a separated acid sludge phase withan acidity of from about to about permitting the resulting admixture tostratify whereby only two layers are formed, an oil layer containingdissolved oil-soluble petroleum sulfonic acids and an acid sludge layer,and separating the layers.

5. A process for the production'of an oil solution of oil-solublepetroleum sulfonic acids, which process comprises intimately contactinga mineral lubricating oil raillnate fraction of naphthenic character,having a viscosity index of at least about 30, and a flash point of atleast about 380 F. and having been obtained as a ramnate fraction from aselective solvent extraction of a naphthenic mineral lubricating oildistillate fraction, with from about 20% to about 50% by weight, basedon the oil charge, of fuming sulfuric acid, at a temperature betweenabout F. and If. for a period of not more than about 10 minutes,thereafter immediately and before the separation of a sludge phase,intimately mixing the resulting reaction mixture with sufllcient waterto yield upon stratification a separated acid sludge phase with anacidity from about 50 to about 70%, permitting the resulting admixtureto stratify whereby only two layers are formed, an oil layer containingdissolved oilsoluble petroleum sulfonic acids and an acid sludge layer,and separating the layers.

HENRY W. ANDERSON.

OTTO A. SAMSON.

AUGUSTUS W. CLARK.

REFERENCES crrnn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,867,778 Terry et al July 19,1932 2,036,469 Field Apr. 7, 1936 2,084,506 Rlosen June 22, 19372,252,957 Averill et al Aug. 13, 1941 2,285,390 Brandt June 9, 1942

1. A PROCESS FOR THE PRODUCTION OF AN OIL SOLUTION OF OIL-SOLUBLE PETROLEUM SULFONIC ACIDS DISSOLVED IN A HIGHLY REFINED LUBRICATING OIL FRACTION, WHICH PROCESS COMPRISES INTIMATELY CONTACTING A MINERAL LUBRICATING OIL RAFFINATE FRACTION OF NAPHTHENIC CHARACTER, HAVING A VISCOSITY AT 100* F. OF AT LEAST ABOUT 400 SSU, A VISCOSITY INDES OF FROM ABOUT 30 TO 60, A FLASH POINT OF AT LEAST ABOUT 380* F., AND HAVING BEEN OBGAINED AS RAFFINATE FRACTION FROM A SELECTIVE SOLVENT EXTRACTION OF A NAPTHENIC MINERAL LUBRICATING OIL DISTILLATE FRACTION, WITH 20% TO 50% BY WEIGHT, BASED ON THE OIL CHARGE, OF 105.5% FUMING SULFURIC ACID, AT A TEMPERATURE BETWEEN ABOUT 75* F. AND 150* F. FOR A PERIOD OF ABOUT 10 MINUTES, THEREAFTER IMMEDIATELY AND BEFORE THE SEPARATIO OF A SLUDGE PHASE, INTIMATELY MIXING THE RESULTING REACTION MIXTURE WITH FROM ABOUT 25% TO ABOUT 80% BY WEIGHT OF WATER, BASED ON THE ACID USED, SELECTED TO YIELD A SEPARATED ACID ON THE ACID USED, SELECTED ACIDITY OF FROM ABOUT 50% TO ABOUT 70%, PERMITTING THE RESULTING ADMIXTURE TO STRATIFY WHEREBY ONLY TWO LAYERS ARE FORMED, AN OIL LAYER CONTAINING DISSOLVED OIL-SOLUBLE PETROLEUM SULFONIC ACIDS AND AN ACID SLUDGE LAYER, AND SEPARATING THE LAYERS. 